Aircrafts require lift to achieve flight. Fixed-wing aircraft generate lift by moving the entire craft through the air, creating a pressure differential across the wings. Rotary-wing aircraft generate lift by rotating the wings, also creating a pressure differential across the wings. To achieve lift-off, enough lift must be generated to overcome the weight of the aircraft.
To reduce reliance on long runways, military aircraft have used solid or liquid fuel rocket cartridges such as rocket-assisted take-off (RATO) or jet-assisted take-off (JATO). These cartridges are fixed to the aircraft and provide a temporary boost of thrust during take-off or landing.